1 Introduction

Section 1: Introduction

1.1Overview and Vision

Curiosity-driven research is at the core of particle physics, a field of science in which we study the building blocks of the subatomic world. In examining these point-like particles and their interactions, we decipher the quantum realm. We also look out into the universe, beyond the visible stars, by building instruments that can illuminate the hidden universe. By studying the very small and the very large, realms that are beyond the limits of normal human perception, we expand our understanding of the world around us and begin to grasp our place in the cosmos. Going beyond phenomena that we can probe using current experiments, we can use theoretical principles to test our current physics understanding and predict new particles and new phenomena; in this way we explore new paradigms in physics.

Within each of these broad themes, we identify compelling questions that define our priorities and drive what instruments we build and what experiments we design. These science drivers change over time, as new discoveries are made and our understanding deepens.

Informed by the community-driven Snowmass planning process, we have identified a new set of three science themes and six science drivers. The drivers evolved from those in the 2014 P5 report.


Elucidate the Mysteries
of Neutrinos

Reveal the Secrets of
the Higgs Boson

in Physics

Search for Direct Evidence
of New Particles

Pursue Quantum Imprints
of New Phenomena


Determine the Nature
of Dark Matter

Understand What Drives
Cosmic Evolution

The US particle physics program would not exist without the sustained support of the Department of Energy (DOE) and the National Science Foundation (NSF). These agencies have nurtured a world-class scientific enterprise. From the discovery of the Higgs boson and the revelation of the neutrino masses to the stunning realization that the expansion of the universe is now accelerating, this effort has revolutionized our understanding of how the universe works. With each new insight into the universe, scientific exploration encounters escalating challenges. The tools and technologies required to meet those challenges become increasingly sophisticated.

Particle physics now operates on a global scale. In isolation, no nation has the financial resources, workforce, or technical capacity required to tackle all of the most pressing questions of our field. Yet that same scientific program is within the grasp of a collaborative global effort. The US is a major player on that stage, currently hosting an international program in the study of neutrinos and charged leptons and in dark matter physics and cosmology. We are a major partner in offshore high-energy collider facilities in Europe and Japan. Each of these initiatives represents a cornerstone in our collective effort to push the boundaries of understanding in particle physics.

Since the 2014 P5 report, the US has made significant investments in expanding its capabilities for groundbreaking discoveries in accelerators and deep underground laboratories. The High-Luminosity Large Hadron Collider (HL-LHC) upgrade is proceeding successfully with critical US contributions. This project addresses key questions about the Higgs boson while searching for new particles and phenomena. Concurrently, the construction of the Deep Underground Neutrino Experiment (DUNE) and the Long Baseline Neutrino Facility (LBNF) is establishing a world-leading experiment for precision neutrino studies. This international mega-project on US soil positions the US as a potential host for future projects. The commissioning of the world’s largest digital camera for the Legacy Survey of Space and Time (LSST) is underway, set to be deployed at the nearly completed Vera C. Rubin Observatory. These projects hold immense potential for producing groundbreaking scientific discoveries in the coming decade.

Mid-scale projects recommended for construction in the previous report, such as the Generation 2 dark matter searches, are either nearing completion or producing exciting new results. Highlights from the mid-scale program include an early data release from the Dark Energy Spectroscopic Instrument (DESI) and the short baseline neutrino (SBN) experiments setting stringent limits on the existence of sterile neutrinos. The Muon g-2 experiment measuring the anomalous magnetic moment of the muon has observed a discrepancy between the measured value and the value predicted by the Standard Model of particle physics, a result that spurs further theoretical developments.

We envision a new era of scientific leadership, centered on decoding the quantum realm, unveiling the hidden universe, and exploring novel paradigms. Balancing current and future large- and mid-scale projects with the agility of small projects is crucial to our vision. We emphasize the importance of investing in a highly skilled scientific workforce and enhancing computational and technological infrastructure. Acknowledging the global nature of particle physics, we recognize the importance of international cooperation and sustainability in project planning. We seek to open pathways to innovation and discovery that offer new insights into the mysteries of the quantum universe.

1.2The Particle Physics Landscape

Particle physics has been increasingly successful in recent decades in describing matter, its interactions, and the 14-billion-year evolution of the universe. Our understanding is captured by the Standard Model and the ΛCDM model, a minimal paradigm of cosmology. The development of these paradigms based on detailed experimental investigations and deep theoretical principles is a triumph and hallmark for the field.

We strive to answer the questions these paradigms cannot yet address. Here we discuss which existing projects remain central to answering key questions in the current scientific landscape as embodied in the 2023 science drivers. We highlight where experimental results demand new initiatives and how theoretical developments of the decade influence our path forward. Finally, we note key investments in accelerator technology, detector instrumentation, computing, and theory crucial to the long-term future of the field.

1.2.1  –Decipher the Quantum Realm

The Standard Model is a remarkable achievement. It provides a comprehensive description of all known fundamental particles and their interactions. In that framework, the Higgs boson is the key to understanding the origin of particle mass, because particles interacting with the Higgs field acquire mass through the Higgs mechanism. However, not all particles behave that way. Neutrinos, the tiniest and most elusive matter particles, once assumed to be massless, appear to defy the predictions of the Standard Model. Their ability to oscillate between flavors is linked to their mass. Yet the connection between the Higgs mechanism and neutrino masses remains a mystery.

Elucidating the mysteries of neutrinos and revealing the secrets of the Higgs boson are essential for understanding the complete picture of particle physics. Each of these science drivers, with its potential to challenge the Standard Model, can act as a key to unlock the quantum realm.

Elucidate the Mysteries of Neutrinos

Neutrino interactions are rare, and their behavior is unique. With technology available today we can detect neutrinos from various sources and produce them in large numbers by accelerating intense proton beams on a target. We can aim the produced neutrinos at detectors from a few kilometers (short-baseline) to more than a thousand kilometers (long-baseline) away to observe how their nature oscillates as they travel.

Experiments in SBN oscillation are more compact in scope, allowing us to pursue specific questions and test new technologies. The SBN effort as recommended by the 2014 P5 is well underway. The design of long-baseline experiments, with detectors placed both close to and far from the beam, allows them to act as many experiments in one. For example, the large volume of a far detector allows it to detect neutrinos from supernovae and the sun in parallel with long-baseline measurements.

We stand on the verge of precision neutrino physics. Recent results from the NOvA and T2K neutrino experiments have confirmed the benchmarks future neutrino experiments must meet. Following the recommendations of the previous P5, the DUNE experiment is under construction, with LBNF leveraging the Fermi National Accelerator Laboratory (Fermilab) proton complex to deliver an intense neutrino beam to the nearly complete Sanford Underground Research Facility (SURF) in South Dakota. DUNE will use massive, cryogenic liquid-argon (LAr) time-projection chambers (LArTPCs) and the intense beam to comprehensively determine the structure of neutrino mixings and the pattern of their masses. The realization and operation of the ProtoDUNE detector prototypes at the CERN Neutrino Platform successfully demonstrated the LArTPC technology for DUNE. This program is poised to acquire large neutrino interaction datasets to challenge the validity of the neutrino oscillation framework.

Both short- and long-baseline programs offer opportunities to search for signatures of unexpected neutrino interactions. They are complemented by small experiments like COHERENT at the Oak Ridge National Laboratory, which recently announced the discovery of a formerly undetected neutrino interaction mode, coherent elastic neutrino-nucleus scattering. A program of neutrino experiments at different scales can ensure that we have the tools and understanding of neutrino interactions and production to enable the potential for discovery of the large facilities being constructed.

If a departure from the current neutrino oscillation framework were to be found, there would be interest in muon storage rings as a neutrino source offering precise and well-characterized neutrino beams. A so-called neutrino factory, whose technology requires research and development (R&D), could propel the neutrino program to new heights of precision oscillation studies.

Reveal the Secrets of the Higgs Boson

The Higgs boson, a unique elementary particle devoid of spin, can interact with all known matter particles. This particle was discovered at the Large Hadron Collider (LHC) with crucial contributions from the US community, just prior to the last P5 report. The existence of the Higgs raises questions about why it is “frozen” in the universe, imbued in a field that gives mass to all elementary particles. To understand the pervasive influence of the Higgs boson, the interactions of the Higgs field with itself, which determine its potential energy, must be thoroughly studied. To date, measurements of the Higgs at the LHC agree with the predictions of the Standard Model. The ATLAS (A Toroidal LHC Apparatus) and CMS (Compact Muon Solenoid) experiments have achieved precise measurements of the Higgs boson mass, confirmed its spin as zero, and measured its lifetime. However, many questions remain about its nature.

Machines like the LHC collide high-energy beams of protons to investigate their fundamental structure and produce particles of higher mass. The HL-LHC upgrade, starting in 2029, will continue to push the boundaries of our understanding of the Higgs boson by increasing the rate of particle collisions to obtain on the order of 400 million Higgs bosons. It is possible that the Higgs could decay to entirely novel particle families connected to physics beyond the Standard Model. Upgraded detectors and advances in software and computing, including artificial intelligence/machine learning (AI/ML), will enable the experiments to detect rare events with higher efficiency and greater purity.

These studies will eventually be limited by the challenges of using proton beams, which are composite objects made of quarks and gluons. The next step is to use electron and positron beams to construct a Higgs factory, which would allow precision measurements of the Higgs boson properties and searches for exotic decays, possibly into dark matter.

Precision studies of the Higgs self-interaction and searches for possible new spinless particles related to the Higgs require much larger energies per fundamental particle (parton) interaction than previously considered: on the order of 10 TeV or more. For lepton colliders, this is the nominal collision energy in the center-of-momentum (CM) frame. For proton colliders, the parton-parton interaction energy is roughly a tenth of the CM energy. We refer henceforth to a 10 TeV parton-center-of-momentum (pCM) collider, since this term applies equally to colliders of all types. Realizing such a collider has impacts beyond the Higgs science driver.

1.2.2  –Illuminate the Hidden Universe

When we look backward in cosmic time, we see a universe very different from the one we know today. The universe has evolved from early moments of rapid expansion (cosmic inflation), which left behind the seeds of its future structure, to intermediate periods dominated by radiation (potentially including unknown light particle species) and dark matter, to our current epoch of accelerated expansion, driven by an unknown component we call dark energy.

The ΛCDM paradigm captures the physics that governs this evolution, which is outside the Standard Model. The two science drivers discussed in this section investigate, and potentially challenge, different aspects of this paradigm.

Determine the Nature of Dark Matter

Our observations of the universe tell us that dark matter exists, but we have yet to determine its nature. Cosmic surveys, including LSST and DESI, probe the distribution of dark matter on a variety of length scales and yield essential data about its properties. The remaining efforts, which use a blend of underground facilities, telescopes, quantum sensors, and accelerator-based probes, focus on detecting particle dark matter candidates.

Until now, the study of dark matter has focused on a class of theoretically well-motivated candidates called weakly interacting massive particles (WIMPs). Generation-2 WIMP dark matter direct-detection experiments recommended in 2014 are in progress. Several are already refining our understanding of dark matter. The next generation of direct WIMP searches will need to be so sensitive that even the elusive neutrinos will be background noise. Reaching this so-called neutrino fog is a clear milestone, at which we cover a large fraction of WIMP theories. Navigating through the neutrino fog will require innovative thinking and R&D of novel technologies. Testing the full range of WIMP theories could require a collider with at least 10 TeV pCM.

These endeavors complement efforts to study non-WIMP dark matter candidates such as the quantum chromodynamics (QCD) axion and hidden sector particles. Since the 2014 P5 report, both theoretical and experimental efforts to study these theoretically well-motivated candidates have matured. These candidates can be searched for even with small-scale experiments.

A class of heavy WIMP dark matter candidates would produce astrophysical signals that reflect their nature. Searches for these signals are part of a broader multi-messenger astrophysics program that maps our universe with light, neutrinos, and gravitational waves. Gamma-ray observatories and the neutrino observatory IceCube have begun to place interesting constraints on these candidates, with substantial advances promised by the far more sensitive next-generation observatories

Understand What Drives Cosmic Evolution

Light from the early universe, known as the cosmic microwave background (CMB), carries the imprint of quantum fluctuations left behind by cosmic inflation. Precision measurements of the polarization of the CMB have already shaped our understanding of inflation and constrained certain neutrino properties. Future surveys, built on well-established techniques, aim to study the imprint of gravitational waves from the inflation era on the CMB. These observations will also constrain new light particle species that may have influenced the universe’s evolution at an early stage.

Galaxy surveys using both imaging and spectroscopy have generated major advances in robust, precise constraints on the accelerated expansion rate of the universe. Current data reveal challenges explaining both early- and late-universe observations within the ΛCDM model. More and higher precision data are needed to understand the implications. The complementary spectroscopic and imaging surveys DESI and LSST will take that next step in exploring the limits of the current cosmological paradigm and determining whether it needs to be modified. DESI is already yielding results, while the LSST is expected to begin in 2025. These experiments will be at their most powerful when combined with each other and with current and future CMB measurements.

Early results from both DESI and LSST will shape future priorities. Together with a potential DESI upgrade, they will inform the design of a next-generation spectroscopic survey by telling us which potential science goals—inflation, late-time cosmic acceleration, light relics, neutrino masses, and dark matter—should be emphasized. LSST science results will drive future survey concepts for the Rubin Observatory. A new technique based on line intensity mapping (LIM) could provide a more complete view of the intermediate period between the period of inflation and our current era of accelerated cosmic expansion. Further study is needed to establish its feasibility.

1.2.3  –Explore New Paradigms in Physics

To gain a deeper understanding of the quantum universe, we must map out unexplored territory beyond the Standard Model and ΛCDM and understand how these two paradigms fit together. Particle accelerators allow us to search for new particles directly and to seek quantum imprints of new phenomena currently beyond our direct reach. This theme is the evolution of the “Explore the Unknown” science driver from 2014.

Search for Direct Evidence of New Particles

Direct searches for new heavy particles using high-energy accelerators have historically been a strong driver of progress in particle physics. A decade of direct searches for new particles at the LHC has produced a treasure trove of data and a wealth of innovative analyses that leverage AI/ML techniques. The discovery of the Higgs boson at the electroweak scale was a triumph, but its small mass remains a mystery. Theoretical and experimental studies indicate that a comprehensive study of the electroweak scale requires colliders with energy of at least 10 TeV pCM, larger than previously assumed.

There is new interest in searching for relatively light but weakly coupled new particles, such as dark matter particles from hidden sector models. Weak coupling implies their production is rare. In this search, our strategy is not to push for the highest possible energy, but for higher-intensity accelerators. Large datasets from a Higgs factory will enable direct searches for feebly coupled light states. In the case of hidden sector dark matter, accelerator-based searches using existing beam dumps are sensitive to benchmark models in the MeV–GeV mass ranges. Intensity upgrades at the proton beamline at Fermilab and focused theory efforts may uncover exciting new lines of inquiry.

Pursue Quantum Imprints of New Phenomena

New phenomena at high energies may be probed through their low-energy quantum imprints. Quantum imprints can manifest in a diverse range of systems, from the relatively light muons and bottom, charm, and strange quarks, to the heaviest known fundamental particles, the top quark and the Higgs boson. The pursuit of these subtle effects requires large data samples. This in turn requires accelerators producing high-intensity beams and precision detectors that can handle the intensity.

The LHCb and Belle II experiments use, respectively, a proton accelerator in Europe and an electron accelerator in Japan for their precision studies of bottom quark systems. Modest upgrades to these experiments will expand their already unprecedented datasets.

The successful completion of the Muon g-2 experiment has left us with a tantalizing hint of new physics. New techniques it developed for producing and transporting muons are applicable to other current and future experiments. Another initiative, Mu2e, searches for a muon changing to an electron without producing any neutrinos. Detection of this charged lepton flavor violation effect would be a revolutionary indication of new physics. Mu2e is nearing completion and poised to begin its first run in 2026, with data-taking continuing intermittently until the end of the decade. Future experiments of this type depend on upgrades to Fermilab’s accelerator complex. R&D would be required to establish the feasibility of these upgrades.

In addition to studying the nature of the Higgs boson, a Higgs factory would be a highly sensitive probe of quantum imprints of new phenomena. Precision measurements of Higgs couplings could yield information about extended Higgs sectors. The large samples of W and Z bosons produced at a Higgs factory would support exceptionally precise studies of electroweak interactions, studies that indirectly probe an energy scale well beyond the HL-LHC.

1.2.4  –Interconnected Opportunities

The science themes and drivers above provide a useful organizing principle, and they are deeply interconnected. For example, studies of cosmic evolution provide critical information not only about dark energy and inflation, but also about light relic particles in the early universe, dark matter, and the scale of the neutrino masses. Complementary measurements obtained across science drivers provide a powerful tool for testing paradigms.

It is perhaps not surprising that a common thread across many drivers is the need for more powerful accelerators. Future studies of neutrinos and charged lepton flavor violation would likely need higher-intensity neutrino, muon, and proton beams. Revealing the secrets of the Higgs boson, characterizing WIMP dark matter, and searching for direct evidence of new particles ultimately requires access to the electroweak scale provided by a collider with pCM energy of 10 TeV.

We do not yet have a technology capable of building a 10 TeV pCM energy machine, but the case for one is clear. Extensive R&D is required to develop cost-effective options. Possibilities include proton beams with high-field magnets, muon beams that require rapid capture and acceleration of muons within their short lifetime, and conceivably electron and positron beams with wakefield acceleration. All three approaches have the potential to revolutionize the field.

A demonstrator facility along the path to a 10 TeV pCM muon collider could fit into the evolution of the accelerator complex at Fermilab. Such a demonstrator might produce intense muon and neutrino beams in addition to performing critical R&D; it could leverage expertise in muon and neutrino beam facilities developed over the past decade. The improved accelerator complex could also support beam-dump and fixed-target experiments for direct searches and quantum imprints of new physics. This R&D path therefore aligns with five of the six science drivers.

1.3Enabling Capabilities and National Initiatives

The US has world-renowned capabilities in particle physics. The national laboratories operate some of the most powerful and sophisticated particle accelerators and detectors in the world and attract some of the brightest minds in science and engineering. Fermilab, the only single-purpose laboratory for particle physics in the US, and Argonne (ANL), Brookhaven (BNL), Lawrence Berkeley (LBNL) and SLAC National Laboratories, with their complementary strengths, provide unique infrastructure and technical capabilities for innovation and discovery in particle physics. US universities play an important role in experimental and theoretical research and in educating the next generation of scientists.

US national initiatives in quantum science, microelectronics, and AI/ML as well as general accelerator and detector R&D have an outsized impact on the field. They lead to new approaches in experiment and theory, and they inspire new experiments and detector upgrades. The US program leads in the application of AI/ML to particle physics, and recent advances in computing are beginning to revolutionize detector development, data taking, analysis, simulation, and accelerator design. The field continues to make substantial contributions to the initiatives on quantum information science and microelectronics. The US is also leading theoretical developments in particle physics, which has been crucial in providing guidance to experiments, interpreting data, and uncovering fundamental theories.

New particle detectors with enhanced sensitivity and accelerators that provide beams at higher energies and intensities have been key to the advancement of the field. Particle physics is the steward of accelerator R&D, together with our partners in nuclear physics, basic energy sciences (BES), accelerator R&D and production, and applied science.

In addition, the development of infrastructure supporting scientific research at the South Pole and the creation of a deep underground laboratory in the US have opened new facilities for discovery science. The South Pole station and surrounding science laboratories are a one-of-a-kind research facility maintained by the US. The unique location provides an unparalleled view of the universe and allows for science that is not accessible elsewhere. The infrastructure and support of the South Pole station and its science program are critical for the study of the CMB and astrophysical neutrinos.

The construction of SURF in the US enables the precision studies of neutrinos and the search for dark matter in an environment shielded by Earth. With SURF, the US has created a premier underground laboratory that is built on a decades-old distinguished history. The realization of this facility adds unparalleled infrastructure capability to the suite of national laboratories in the US. SURF enables the US to be an international host for the neutrino and dark matter experiments recommended in this report.

1.4Impact on Society

Pushing the frontiers of human knowledge in particle physics requires global scientific collaborations, state-of-the-art research facilities, and infrastructure to support the ambitious projects that advance science. In collaborating on and coordinating large international efforts, scientists connect irrespective of their backgrounds, making particle physics an enterprise that transcends borders, boundaries, cultures, and societies.

Discoveries of new laws of nature that deepen our understanding of the inner workings of the universe not only excite scientists but continue to amaze the public and inspire many people to pursue careers in science, technology, engineering, and mathematics—the STEM fields. Nurturing and developing the next generation of scientists and training a highly-skilled workforce are important benefits to society.

Particle physics has a long-proven record of creating new technologies that have revolutionized our daily experience, such as the world wide web and life-saving medical applications—from cancer treatment to medical imaging—derived from particle accelerator and detector technologies. The tools developed for particle physics research also impact society through their adoption by other scientific fields. Applications in chemistry and materials science, for instance, have led to innovations in drug discovery and the design and realization of novel materials.

Particle physics provides a training ground for a skilled workforce that drives not only fundamental science, but quantum information science, AI/ML, computational modeling, finance, national security, and microelectronics. The US has led the way in many groundbreaking discoveries in particle physics and is poised to continue its leadership role with sustained investment.

1.5Process and Criteria

The 2023 P5 is charged with developing a fiscally viable 10-year strategic plan for US particle physics. The charge further specified that this 10-year plan should fit in the context of a 20-year vision (see Appendix 1).

The recommended program must reflect the scientific interests of the particle physics community. The 2021 Snowmass Community Planning Exercise, organized by the Division of Particles and Fields of the American Physical Society, provided initial input to the deliberations of the P5 panel. To fully capture the views of the community, the panel solicited additional input through town hall meetings, laboratory visits, and individual communications. The panel was especially encouraged by the active participation of early career members in the community-driven planning process. They represent the future of our field and are essential to the realization of the goals and aspirations detailed in this report.

During the panel’s deliberations, there was consensus that the overall program should enable US leadership in core areas of particle physics. The program should leverage unique US facilities and capabilities, engage with core national initiatives to develop key technologies, and develop a skilled workforce for the future that draws on US talent. Effective engagement and leadership in international endeavors were also considerations.

The community presented P5 with more inspiring and ambitious projects than fiscal reality could accommodate. In selecting projects, the panel considered a project’s individual scientific merit and potential for transformational discovery as well as how well the project met criteria for the overall program.

The DOE provided the panel with two budget scenarios for High Energy Physics (HEP) derived from realistic near-term budget projections. The baseline scenario assumes budget levels for HEP for fiscal years 2023 through 2027 that are specified in the Creating Helpful Incentives to Produce Semiconductors (CHIPS) and Science Act of 2022. The baseline budget scenario then increases by 3% per year from fiscal year 2028 through 2033. The less favorable scenario assumes increases of 2% per year from fiscal year 2024 to 2033.

The panel was asked to develop DOE programs consistent with these scenarios. Prioritization of projects that would receive funding from the DOE therefore had to consider both project cost and the uncertainties in that cost related to the project’s technical readiness and design maturity. For projects where the US contribution is expected to come entirely from NSF, the panel was only asked to consider scientific relevance to the US particle physics program. We note that in a number of cases, the NSF science case for a jointly funded project extends beyond particle physics into astrophysics.

The panel categorized projects as small (<$50M), medium ($50M–250M), and large (>$250M) based on the US contribution to their construction cost. In the large and medium categories, initiatives were first prioritized based on individual scientific merit, then assessed on project maturity and technical risk. The balance of project timescales was also considered, in order to ensure delivery of scientific results throughout the decade and opportunities for scientists at all career levels. The final prioritization holistically considered the cost of construction, commissioning, operations, and related research support, distributed over a 10- to 20-year period. As per the charge, the panel generally did not consider individual small projects, but did note areas where such projects could be particularly effective. As part of this process, the panel established budget profiles in FY23 dollars with assumptions on inflation as described in section 8.

To help the P5 panel better understand costs, schedules, and risks of the large projects, a subcommittee was convened with project management and technical experts from the community. The subcommittee provided an independent assessment of the cost range, schedule, and risks of the major projects. That input was used to assess the most likely cost scenarios and reduce the chance of unexpected budget overruns from current and new projects into the next decade.

The panel also considered broader questions of how this program should be carried out. We discuss ethical conduct in the field and present recommendations to build a more inclusive and respectful community that draws on all talent in the nation and beyond.

P5 worked completely independently from the “Elementary Particle Physics: Progress and Promise (EPP2024)”, panel that will deliver its report later in 2024, although we shared the same inputs from the community. EPP is convened by the National Academy of Sciences and charged to deliver a view of elementary particle physics over even longer time scales and unconstrained by financial considerations.

1.6Roadmap to the Report

Section 1 introduces the science drivers and our vision for particle physics as well as the process and criteria for the P5 deliberations.

The recommendations are presented in section 2. Brief discussions expand on the infrastructure and expertise required to carry them out as well as the importance of international and inter-agency partnerships. The subsequent sections discuss how the program can be adapted to alternative budget scenarios, both for less and more favorable funding. Sections 3, 4, and 5 describe the impact of these recommendations on the three science themes but are not intended to be comprehensive reviews of the science opportunities.

Additional area recommendations are made in section 6, which highlight theoretical, computational, and technological areas where sustained investments can advance the future of science and technology. In those recommendations, the panel explicitly indicates the increase in annual funding needed to achieve the field’s 20-year goals—increases that should be achieved through a ramp, lasting no more than five years, between current and new funding levels. Section 7 expands on the recommendation supporting a technologically advanced workforce. Additional budgetary considerations are described in section 8.